Hydrocarbon oil treatment



Patented Mar. 17, 1936 NITED STATES 7 AT'ENT OFFICE No Drawing. Application June 28, 1933, Serial No. 678,104

19 Claims.

The present invention relates to the art of mineral oil refining, and has particular reference to the separation of crude petroleum or petroleum products into fractions of different chemical composition while of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products, particularly oils of substantial viscosity, are separated into .various fractions by means of fractional extraction with an aliphatic sulfone, or a mixture of solvents containing substantial amounts of aliphatic sulfones. Specific examples of vsuch compounds as may be employed in my process are dipropyl sulfone and dibutyl sulfone.

It is recognized in the art that mineral oils, such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series ofcompounds, such for example, as paraffins of the general formula CnH2n+2, olefins of the general formula Cal-I211, hydroaromaticsand polymethylenes of the same empirical formula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large number of individual compounds ofeach series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are-generally classified into three groups,na mely, paraflinic base, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the paraffin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and a lowhydrogen to'carbon ratio. Mixed base crude oils, such as are obtained from the mid-continentoil fields, contain hydrocarbons in proportions intermediate these two extremes. a

The variance in the proportion of the different series of hydrocarbons inparaffinic, naphthenic, and mixed base oils is evidenced by the physical properties of thevarious oils and particularly by the relationship of the specific gravityto the viscosity of one oil as compared with another. For example, oil derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt Universal at 100 F., will show a specific gravity at 60 F., of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf Coast area,

Will show a specific gravity of about 0.933 at 60 log (V38) or G=0.24+0.755a+0.022 log(V-35.5) in which G is the specific gravity at 60 F., V and V are respectively Saybolt universal viscosities at 100 F. and 210 F., and a is a constant known as the viscosity-gravity constant. Viscous fractions from each of the different types of crude have difierent viscosity-gravity constants. While, in general, viscous fractions from a single crude have substantially the same viscosity-gravity constant, such constant is lower for fractions of the paraffinic crudes than is the constant for fractions of the .naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubricating oils by J. B. Hill and H. B. Coats, which will be found in volume 20, page 641 et seq., Industrial and Engineering Chemistry for June, 1928, explains the determination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an index of the parafiinicity or naphthenicity of viscous oils, since when a given crude is distilled, the fractions thereof collected, and the specific gravity and the viscosity of each of the viscous fractions determined, such specific gravities and viscosities substituted in the formula, and the viscosity-gravity,constants of the fractions calculated, it will be found that such constants are substantially the same.

fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067

Burbank (Mid-Continent) 0.8367 Guadalupe (Gulf Coast) 0.8635 Mirando (Gulf Coast) 0.9025

While the above figures indicate the viscositygravity constants of specific oils from several types of crudes, it is tobe understood that for any particular type of crude such constant may be within a range between values above and below the constant of the typical crude given. For example, viscous oils resulting from the distillation of mid-continent crudes have viscosity-gravity constants ranging from about 0.835 to about .855, whereas the viscous fractions resulting from the distillation of Pennsylvania type crudes range from about .805 to about .828, and in most instances, are below .820. Oils are increasingly paraifinic as their viscosity-gravity constants decrease.

My invention is based upon the discovery that oils containing both the parafiinic series of hydrocarbons and the various naphthenic series may be fractionally extracted with an aliphatic sulfone. The various series of hydrocarbons possess a differential solubility in such solvent, the naphthenic hydrocarbons being much more soluble therein than the paraffinic hydrocarbons. By means of extraction with such solvent, it is therefore possible to effect a partial separation of the naphthenic hydrocarbons from the paraflinic, and to obtain from an oil containing both classes of hydrocarbons, an oil which is much more parafiinic than the original oil and one which is much more naphthenic. By my invention, for example, it is. possible to produce an oil of the quality normally obtained from Appalachian crude, from crudes of the mixed base type from the mid-continent area, and, conversely, to ob tain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the Gulf Coast area. In general, from oils from any source there may be obtained by my process, oils which are respectively more paraffinic and more naphthenic than the oils normally obtained from such source by distillation.

In accordance with my invention, I first mix the oil to be treated with a suitable proportion of an aliphatic sulfone at a temperature such that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture to a temperature at which separation of the liquid into a two-layer system will take place. The upper layer will contain a relatively small amount of the solvent dissolved in the paraffinic portion of the oil while the lower layer will contain the more naphthenic portion of the oil dissolved in the solvent. Or, I may agitate the mixture of solvent and oil at temperatures at which the liquids are only partially miscible, and thereby effect solution of the naphthenic portion of the oil in the solvent. In either of the above procedures I may take advantage of the principles of countercurrent extraction.

After the extraction proper, I effect separation of the two layers which form, by any suitable procedure, as for example, by decantation. I then remove from each of the separated layers, the portion of solvent which each contains by suitable procedure, such as by vacuum distillation, thereby to obtain two oils of similar distillation ranges but of different chemical compositions and different physical characteristics.

Before removing the solvent from the upper and more parafiinic layer, I may add a further quantity of solvent and repeat the extraction, thereby to remove additional naphthenic constituents from said layer. The extraction step may be repeated any desired number of times, each repetition producing an oil of higher paraffinicity as evidenced by its lower viscosity-gravity constant.

Where substantial quantities of waxy hydrocarbons belonging to the true paramn series (CnH2n+2) are present, such hydrocarbons remain in the upper or more paraffinic layer and may cause such layer to be solid or semi-solid. Such layer may be separated into solid and liquid hydrocarbons by any of the Well-known dewaxing processes such as by cold-settling or by centrifuging. In many instances it may be advantageous to dewax the oil prior to extraction. However, it is to be understood that in accordance with my invention, dewaxing may be efiected either prior or subsequent to extraction.

My invention will be further understood from the following specific examples: 7

100 parts of a Mid-Continent distillate having a viscosity of 154 second Saybolt universal at 210 F., a specific gravity of 0.9176 at 60 F., and a viscosity-gravity constant of 0.836 was mixed with 300 parts of dibutyl sulfone and heated to slightly above the temperature of complete miscibility. The homogeneous liquid which resulted was cooled with agitation to C., and allowed to settle, whereupon a two-layer system formed. After separation the layers were each freed of solvent by vacuum distillation. The undissolved oil fraction comprising 47.7 of the stock had a viscosity of 1&5 seconds Saybolt universal at 210 F., a specific gravity of 0.9001, and a viscositygravity constant of 0.815. The dissolved oil fraction comprising 52.3% of the stock had a specific gravity and a viscosity-gravity constant higher than that of the original oil stock, thus indicating an increase in naphthenicity.

parts of the same Mid-Continent distillate having a viscosity of 154 seconds Saybolt universal at 210 F., a specific gravity of 0.9176 at 60 F., and viscosity-gravity constant of 0.836, was extracted in the above described manner with 100 parts of dibutyl sulfone. The resulting undissolved oil fraction comprising 75.5% of the stock had a viscosity of 143 seconds Saybolt universal at 210 F., a specific gravity of 0.9082 and a viscosity-gravity constant of 0.825, and the dissolved oil fraction comprising 24.5% of the stock had a specific gravity and viscosity-gravity constant higher than that of the original oil stock.

From the above examples it will be noted that by extraction of an oil with an aliphatic sulfone, there may be obtained oil fractions which are respectively more paraifinic and. more naphthenic than the original oil. By repetition of the extraction process upon the undissolved fraction, oils of even greater paraffinicity will result.

My process is practically independent of the particular nature or source of the crude oil or oil fraction to be extracted. There may be produced by my process oil products of desired characteristics from oils which by distillation will not produce such products.

Hereinabove, mixtures of solvents have been referred to. It is to be understood that in such mixtures the constituents will not react with one another nor with the oil upon which they are to be used, and that such mixtures will contain substantial amounts 015 an aliphatic sulfone.

For brevity, herein and in the appended claims aliphatic sulfone is employed in a generic sense to include one or a mixture of aliphatic sulfones, or a mixture of solvents containing substantial amounts of aliphatic sulfones.

Also, when herein and in the appended claims, oil is specifically referred to as being viscous, it is to be understood that the oil is of substantial viscosity, i. e., of the order of 50 seconds Saybolt universal at 100 F., or more.

What I claim is:

1. In the art of refining mineral oils, the process which comprises separating an oil containing paraffinic and naphthenic hydrocarbons into fractions respectively richer in paraflinic and naphthenic compounds by extracting said oil with an aliphatic sulfone.

2. In the art of refining mineral oils, the proces which comprises adding an aliphatic sulfone to an oil containing paraifinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solutionto form a two-layer system, and separating the upper layer from the lower layer.

3. In the art of refining mineral oils, the process which comprises adding an aliphatic sulfone to an oil containing parafilnic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solution, cooling the solution to form a two-layer system, removing the lower layer, and similarly retreating the upper layer with an aliphatic sulfone.

4. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing paraffinic and naphthenic hydrocarbons into contact with an aliphatic sulfone thereby to effect solution of a portion richer in naphthenic hydrocarbons in the aliphatic sulfone, separating the. solution so formed from the remainder of the oil, and removing the said sulfone from both portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

5. The process for separating mineral oils containing parafiinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with an aliphatic sulfone thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons inthe aliphatic sulfone, separating the solution so formed from the remainder of the oil, and distilling the aliphatic sulfone from both of the portions of the oil, there by to obtain fractions of the oil respectively richer in paraflinic and naphthenic hydrocarbons.

6. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contact with an aliphatic sulfone thereby to effect solution of a portion richer in naphthenic hydrocarbons in said sulfone, separating the solution so formed from the remainder of the oil, and retreating the oil remaining with additional amounts of an aliphatic sulfone.

7. The method for producing paraifinic lubricating oil from mixed base crude which comprises distilling the crude and bringing a portion thereof into contact with an aliphatic sulfone, thereby partially dissolving the oil, separating the sulfone solution of oil so treated, and removing the said sulfone from the treated oil.

8. In the art of refining mineral lubricating oil containing parafiinic and naphthenic hydrocarbons, the step of iractionally extracting the oil with an aliphatic sulfone, to effect a separa tion of fractions respectively richer. in paraflinic and naphthenic compounds. 7

9. The process of treating a Viscous fraction of a crude oil of one type containing paraffinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater content of paraflinic hydrocarbons, which comprises extracting the viscous fraction with an aliphatic sulfone, and separating the oil so treated into portions respectively richer in paraffinic and naphthenic hydrocarbons.

10. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having the quality of a corresponding fraction of a paraffinic base crude, which comprises extracting the viscous fraction with an aliphatic sulfone, and separating the oil so treated into portions respectively richer in paraflinic and naphthenic compounds.

11. In the art of refining mineral oils, the process which comprises adding an aliphatic sulfone to a viscous oil liquid at ordinary temperatures containing parafiinic and naphthenic hydrocarbons, heating the mixture to a temperature sufiicient to effect solution, cooling the solution to a temperature sufiicient to form two layers respectively richer in naphthenic hydrocarbons.

and parafiinic hydrocarbons other than wax, and separating the upper layer richer in paraflinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

12. In the art of refining mineral oils, the process which comprises bringing an aliphatic sulfone into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing paraffinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation.

13. In the process of decreasing the viscositygravity constant of a viscous mineral oil the step which comprises extracting the oil with an aliphatic sulfone.

14. In the process of decreasing the viscositygravity constant of a viscous oil at least 0.015, the step which comprises extracting the oil with an aliphatic sulfone.

15. In the process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.835 to reduce the viscosity-gravity constant by at least 0.015, the step which comprises fractionally extracting said viscous oil with an aliphatic sulfone.

16. In the process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.835 toproduce an oil having a viscosity-gravity constant less than 0.816, the step which comprises fractionally extracting said viscous oil with an aliphatic sulfone.

17. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing paraflinic and naphthenic hydrocarbons into contact with dibutyl sulfone thereby to efiect solution of a portion richer in naphthenic hydrocarbons in 'the solvent, separating the solution so formed from the remainder of the oil, and removing the sulfone from both porinto portions respectively richer in parafinic and naphthenic hydrocarbons.

19. The method for producing aparaffinic lubricating oil from a mixed base crude oil which comprisesdistilling the crude and bringing a portion thereof into contact with dibutyl sulfone, thereby partially dissolving the oil, separating the sulfone solution of the oil so treated, and removing the sulfone from the treated oil.

STEWART S. KURTZ, JR. 

